On 11/4/2023 12:15 AM, Krishna Kurapati PSSNV wrote:
On 11/3/2023 8:44 PM, Bryan O'Donoghue wrote:
On 17/10/2023 14:18, Krishna Kurapati wrote:
The following are the requirements aimed in this implementation:
1. When enum in device mode, Glue/core must stay active.
2. When cable is connected but UDC is not written yet, then glue/core
must be suspended.
3. Upon removing cable in device mode, the disconnect event must be
generated and unblock runtime suspend for dwc3 core.
Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
Hi Bryan,
What happens to this code if you
static int count;
1. sleep in dwc3_probe for 10 milliseconds
2. return -EPROBE_DEFER
3. if count++ < 5 goto 1
i.e. if we simulate say waiting on a PHY driver to probe in dwc3_probe()
The vendor hooks are used in __dwc3_set_mode and role_switch_set calls
in core and drd files respectively. These are invoked only if we are OTG
capable. The drd_work is initialized in core_init_mode which is called
at the end of dwc3_probe. If dwc3_probe fails and gets deferred before
that, none of the vendor hooks will be fired and dwc3_qcom_probe is also
deferred.
However I see that if core_init_mode fails (the cleanup is already done
in drd to prevent set_role from getting invoked already), I need to
cleanup vendor hooks in error path of dwc3_probe().
and what happens if we introduce a 100 millsecond sleep into
dwc3_qcom_probe() - and run a fake disconnect event from
dwc3_qcom_probe_core() directly ?
In other words if make it that dwc3_probe() completes and struct
dwc3_glue_ops->notify_cable_disconnect() fires prior to
dwc3_qcom_probe_core() completing ?
i.e. I don't immediately see how you've solved the probe() completion
race condition here.
Just wanted to understand the situation clearly. Is this the sequence
you are referring to ?
1. dwc3_probe is successful and role switch is registered properly.
2. added delay after dwc3_qcom_probe_core and before interconnect_init
3. Between this delay, we got a disconnect notificiation from glink
4. We are clearing the qscratch reg in case of device mode and
un-registering notifier in case of host mode.
If so, firstly I don't see any issue if we process disconnect event
before qcom probe is complete. If we reached this stage, the clocks/gdsc
is definitely ON and register accesses are good to go.
If we are in host mode at this point, we would just unregister to
usb-core notifier and mark last busy. If we are in device mode, we would
just clear the hs_phy_ctrl reg of qscratch. After the 100ms delay you
mentioned we would call dwc3_remove anyways and cleanup the vendor
hooks. But is the concern here that, what if we enter runtime_suspend at
this point ?
Just to clarify one more thing. The probe completion requirement came in
because, before the device tree was flattened, dwc3-qcom and core are
two different platform devices. And if the dwc3 core device probe got
deferred, dwc3-qcom probe still gets successfully completed. The glue
would never know when to register vendor hook callbacks to dwc3-core as
it would never know when the core probe was completed.
That is the reason we wanted to find out accurate point where core probe
is done to ensure we can properly register these callbacks.
Regards,
Krishna,
